True Amplitude Seismic Imaging Beneath Gas Cloud Using Full Waveform Transmission Deconvolution

Conventional imaging processes for a situation with a gas cloud do not offer satisfactory solutions. Due to the complex wave propagation through the anomaly and the transmission imprint on the reflections from below these complexities, the image below the anomaly is usually not properly recovered. We aim at constructing full waveform transmission operators (including the codas) from the gas cloud reflection response via an effective medium representation. True amplitude imaging is achieved via multi-dimensional deconvolution for these full waveform transmission operators. The feasibility of 1.5D non-linear full waveform inversion using a genetic algorithm (GA) and 2D transmission deconvolution has been successfully demonstrated (Ghazali et al., 2009a; Ghazali et al., 2009b; Ghazali et al., 2009c). The results are encouraging enough for an extension of the inversion process to the full 2D case, and eventually to 3D. However, extending this approach to a multi-dimensional non-linear full waveform inversion is not simple or straightforward. In this paper, we present a feasibility study on 2D synthetic data, for which the operators are obtained by forward modeling through the gas cloud region. For the 1.5D case, it is demonstrated that a targetoriented full waveform inversion process to obtain effective gas cloud for medium parameters is viable.